Until natural gas was an available energy source, it was manufactured at local gas plants now known by the lovely acronym of MGP (manufactured gas plant). At the time (roughly 1870 – 1930) manufactured gas was considered to be cutting edge technology. Coal and oil were the raw materials, and the gas that was created helped transform city life – for example, by powering gas street lamps. Unfortunately, gas wasn’t the only thing created at MGPs and some of the byproducts are now considered to be a health hazard (think VOCs and PAHs).
What does this have to do with you? Believe it or not, even though these plants stopped operating by the 1930’s, the currently responsible legal party – Pacific Gas & Electric – is still doing site investigations, monitoring, and remediation where appropriate.
The manufactured gas plants in the Marina neighborhood were destroyed in the 1906 earthquake, and then buried over again during the 1915 Panama-Pacific International Exposition. So residential homes, businesses, and parks currently rest on land that was once used to manufacture gas. PG&E is emphatic that “There is no indication that PG&E’s former MGP sites pose any health concerns to the public, based on our testing, experience, and extensive review of medical literature.”
PG&E and the State of California came to a ‘voluntary agreement’ in 2010 that requires PG&E to continue monitoring and sampling for residual materials that may be present at these sites. Of the five location in San Francisco, the Marina sites are by far the most residential, so it is something you should be aware of if you are considering buying or selling a home in the Marina district. As for the other sites? The fisherman wharf site is now home to a hotel, the Potrero site is occupied by a warehouse, and the central waterfront site is under remediation (the former Potrero Power Plant).